CHAPTER IX 

 THE NEMATOGNATHI, OR CATFISHES 



HE Nematognathi. The Nematognathi (vrjpa, thread; 

 yvaBos, jaw), known collectively as catfishes, are 

 recognized at once by the fact that the rudimentary 

 and usually toothless maxillary is developed as the bony base 

 of a long barbel or feeler. Usually other feelers are found around 

 the head, suggesting the "smellers" of a cat. The body is 

 never scaly, being either naked and smooth or else more or less 

 completely mailed with bony plates which often resemble 

 superficially those of a sturgeon. Other distinctive characters 

 are found in the skeleton, notably the absence of the subopercle, 

 but the peculiar development of the maxillary and its barbel 

 with the absence of scales is always distinctive. The symplectic 

 is usually absent, and in some the air-bladder is reduced to a 

 rudiment inclosed in a bony capsule. In almost all cases a 

 stout spine exists in the front of the dorsal fin and in the front 

 of each pectoral fin. This spine, made of modified or coalescent 

 soft rays, is often a strong weapon with serrated edges and 

 capable of inflicting a severe wound. When the fish is alarmed, 

 it sets this spine by a rotary motion in its socket joint. It can 

 then be depressed only by breaking it. By a rotary motion 

 upward and toward the body the spine is again lowered. The 

 wounds made by this spine are often painful, but this fact is 

 due not to a specific poison but to the irregular cut and to the 

 slime of the spine. 



In two genera, Noturus and Schilbeodes, a poison-gland exists 

 at the base of the pectoral spine, and the wound gives a sharp 

 pain like the sting of a hornet and almost exactly like the sting 

 of a scorpion-fish. Most of the Nematognathi possess a fleshy 

 or adipose fin behind the dorsal, exactly as in the salmon. In 



IT 12 177 



